Conventional stepladders having two foldable sections hinged together at the top are usually somewhat unstable in spread-apart position when a person is working and moving about on the ladder, as the sections have a tendency to fold or walk toward closed position. Prior mechanisms for correcting this tendency and stabilizing the stepladder in spread-apart position have included costly and complicated linkages and slide arrangements which are frequently ineffective and sometimes dangerous.
The same difficulties have been experienced with extension stepladders wherein one of the two sections may optionally be extended for using the ladder as an extension ladder by leaning the extended section against a wall or the like, with the added complication that not only must the hinge mechanism permit the extension, but the stabilizing mechanism for the stepladder use must not interfere with extension ladder use.